Field of the Invention
The present invention relates to a lithography apparatus, and a method of manufacturing an article.
Description of the Related Art
One of lithography apparatuses is a drawing apparatus which performs drawing on a substrate using charged particle beams. The drawing apparatus irradiates the substrate with charged particle beams emitted from a charged particle optical system and controls (deflects) the charged particle beams, thereby drawing (forming) an arbitrary pattern on the substrate (of the resist). The charged particle optical system is housed in an optical system barrel (optical system housing) and supported by a vacuum chamber.
High drawing positional accuracy is required for the pattern drawn on the substrate by the drawing apparatus. However, the drawing positional accuracy of the pattern decreases when, for example, a position fluctuation caused by the vibration of the optical system barrel of the charged particle optical system occurs. In a conventional exposure apparatus, as disclosed in Japanese Patent Laid-Open No. 2004-153092, so-called optical system barrel reference measurement which includes a measurement system for measuring the position of the optical system barrel housing a projection optical system and corrects an exposure position (pattern formation position) in real time based on a measurement result by the measurement system is performed. This optical system barrel reference measurement measures, using a plurality of interferometers, not only the position fluctuation of the optical system barrel in a translation direction but also the orientation fluctuation of the optical system barrel around each translation direction.
In order to increase throughput, some drawing apparatus employs a multicolumn method in which a plurality of charged particle optical systems are arranged in at least one of the first direction and the second direction. In this case, a substrate stage arranged under the plurality of charged particle optical systems can move in the first direction or the second direction, and simultaneously irradiate a substrate held by the substrate stage with a plurality of charged particle beams emitted from each of the plurality of charged particle optical systems. Even in such a multicolumn drawing apparatus, optical system barrel reference measurement is needed to improve drawing positional accuracy.
In a conventional exposure apparatus, the length of a side of an area on the substrate that is exposed at once is about 30 mm at the maximum. On the other hand, in the multicolumn drawing apparatus, the length of a side of an area on the substrate with which the plurality of charged particle beams are irradiated simultaneously may be, for example, about 250 mm. A rotation measurement error around the optical axis of each charged particle optical system in optical system barrel reference measurement will be the target positional error of each charged particle beam to irradiate the substrate. The target positional error depends on the rotation measurement error and the area (the length of a side thereof) on the substrate with which the plurality of charged particle beams are irradiated simultaneously. In the drawing apparatus, therefore, since the length of a side of the area on the substrate with which the plurality of charged particle beams are irradiated simultaneously is long, the drawing positional accuracy (the positioning precision of a beam on the substrate) decreases.